Method of manufacturing contact springs

ABSTRACT

Method and apparatus are disclosed for welding electrical contacts onto springs. A billet of contact material is first welded to two contact springs and, after welding, is cut in two parts leaving one contact on each spring. The method provides rapid and precise means for attaching precious metal contacts to spring material.

United States Patent 1191 Bannister et al.

[ METHOD OF MANUFACTURING CONTACT SPRINGS [75] Inventors: Royston WalterBannister; Frank Taylor, both of Kent, England [73] Assignee:International Standard Electric Corporation, New York. NY.

22 Filed: May 9,1974

[21] App1.N0:468,34l

[30] Foreign Application Priority Data May 31, 1973 United Kingdom .126001/73 [52] US. Cl 29/630 C; 29/628; 29/630 R; 1 [3/1 19 [51] Int. ClH0lr 9/00 [58] Field of Search. 29/628. 630 R 630 B 630 C. 29/203 R. 203D, 203 S, 622, 33 R, 33 M; 72/324, 332, 338'. 113/119 [56] ReferencesCited UNITED STATES PATENTS 2,] 29845 9/1938 King et a1 .1 29/630 C [451July 15,1975

3.114.828 12/1963 Gannoe 29/630 C 3.229357 1/1966 Burstin i i o 29/630 C3.382575 5/1968 Gannoe 4 a v A A 4 113/119 3,475.8l6 I 1/1969 Willoughby29/630 R 1485.994 12/1969 Swager et 31 i t t 29/630 C 3.803.71 I 4/1974Dubuc et a1v .i 29/630 C Primary Examincr-C. W. Lanham Ass/stun!E.rmrzirwr-]ames R. Duzan Attorney Agent. or Firm.1ohn T. O'Halloran;Menotti .1. Lombardi, Jr, Richard A. Menelly [57] ABSTRACT Method andapparatus are disclosed for welding electrical contacts onto springs. Abillet of contact material is first welded to two contact springs and.after welding. is cut in two parts leaving one contact on each spring.The method provides rapid and precise means for attaching precious metalcontacts to spring material. 1

2 Claims, 21 Drawing Figures METHOD OF MANUFACTURING CONTACT SPRINGSFIELD OF THE INVENTION This invention relates to welding contacts oncontact springs, particularly but not exclusively for telephoneswitching relays.

SUMMARY OF THE INVENTION According to one aspect of the presentinvention there is provided a method of manufacturing contact springs byproviding a billet of contact material and two springs, supporting thebillet and springs so that the billet touches the two springs, passingan electric welding current to weld the billet to both springs, and thenforming the billet into separate portions such that each spring is leftwith a contact made from the billet.

Conveniently, if each spring is bifurcated, two billets can be weldedsimultaneously.

According to another aspect of the present invention there is providedapparatus for manufacturing contact springs in a continuous processcomprising a welding station, a cutting station and a coining station,first transfer means for transferring first and second contact springsthrough the stations, second transfer means for transferring a contactbillet to the welding station, and holding means for holding the billetagainst and between opposed contact portions of the springs for weldingto both springs at the welding station, the cutting and coining stationsbeing effective to form the billet into separate portions such that eachspring is left with a contact made from the billet.

Preferably the contact material is in the form of wire fed to a billetcutting station, there being a circular disc having a slotted peripheryarranged to pass through said cutting station and pick up said free endportion in a peripheral slot, there being a cutter to cut a free endportion of the wire so that after cutting the billet is carried awayfrom the cutting station in the slot towards the welding station whereit is welded to the springs.

The springs are punched out of strips of contact spring material. Thesprings can remain integral with the respective strip, or they can beseparated and stacked prior to feeding through the contact making andforming stations. The springs are fed through the contact weldingstation and then through a cutting station where the billet is cut sothat the contact springs become separated. The springs pass through acoining station where the unfinished contacts are coined to shape. Theyare then stacked or if integral with the strips rewound on respectiveseparate reels.

In order that the invention can be clearly understood reference will nowbe made to FIGS. I-6 filed with the Provisional Specification and FIGS.7-I0 of the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. lA-lG illustrate schematicallythe billet and contact forming process according to an embodiment of thepresent invention;

FIGS. 2A2D show schematically parts of an apparatus for carrying out theforming process of FIG. 1;

FIG. 3 shows schematically apparatus incorporating the parts of FIG. 2;

FIGS. 4A and 4B are respectively a plan and side view of a complete highspeed contact forming and welding machine incorporating the featuresoutlined in FIGS. 1, 2 and 3;

FIG. 5 shows in greater detail typical contact springs, during a stageof manufacture according to an embodiment of the present invention;

FIG. 6 shows a welding head arrangement suitable for use in theembodiment of FIG. 4;

FIG. 7 shows schematically an alternative embodi ment of the presentinvention;

FIG. 8 shows in greater detail part of the embodiment of FIG. 7;

FIGS. 9 and 9A show another part of the embodiment of FIG. 7 in greaterdetail; and

FIG. 10 is a schematic section of part of FIG. 9 on a different scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, preciousmetal wire I is fed from a reel to a cutting station where a cut 2 formsa billet 3 for transfer to a welding station (FIG. IA and FIG. 1B). Thebillet 3 is located between two springs 4 and 5 (FIG. 1C) and is weldedto the springs 4 and 5 at the welding station (FIG. ID).

The springs and welded billet move on to a cutting station where a cut 6(FIG. 1E) forms the welded billet into two separate contacts 7 and 8(FIG. IF). The contacts are subsequently coined to produce the finishedcontacts 9 and 10 (FIG. 1G).

The above description and FIG. 1 describes the basic process andapparatus and further details of various other aspects of the processand apparatus will be more fully explained in the subsequent drawings.

Referring to FIG. 2, FIG. 2A shows the use of two rotating cutters 11and 12 for cutting a billet 3 from the fed wire I. A carrier plate 13carries the billet in a slot I4 to a welding station illustratedschematically in FIG. 28. Here two rolling electrodes 15 and I6 supplywelding current from a supply (not shown) through the springs 4 and 5and the billet 3 as the springs and billet pass between the rollers.From the welding station the springs and welded billet pass to a cuttingstation illustrated schematically in FIG. 2C where the billet is cutinto the separate unfinished contacts 7 and 8.

From this cutting station the springs and unfinished contacts passthrough a coining station illustrated schematically by FIG. 2Dcomprising two rollers 17 and 18, the roller I7 having recesses such as19 having the shape of the finished contacts such as 9.

The springs are connected together and form part of an integral stripwhich is unwound from a first roller pass through the welding andforming apparatus and are wound onto a second roller (see FIGS. 3, 4 and5).

Referring to FIG. 3 the precious metal contact wire I is fed fromseveral reels of the wire (not shown) via a wire feeder 20 to a rotatingwire feed turret 21 which is rotationally fast with a cutter wheel 21(similar to wheel 11, FIG. 2A). The turret 20 carries free end portions,such as 22, into the cutting station where they are picked up by slotssuch as 23 in the carrier plate 24 (similar to carrier plate 13 in FIG.2).

The cut billets are held captive in the slot such as 23 by means of acover plate 25 and base 26 and intermediate pressure plate 27, duringtheir transfer round to the diametrically opposed welding stationillustrated schematically by rotary welding electrodes 28 and 29(corresponding to 15 and 16 in FIG. 2). Pre-punched strips 30 and 31 oftransverse springs (such as 4 and 5, FIG. 2) are advanced through thewelding station and to the cutting station represented schematically bycooperating cutter wheel 32 and 33 (corresponding to the wheels shown inFIG. 2C). Although not shown in FIG. 3 each contact could then besubjected to a coining operation as illustrated in FIG. 2D, oralternatively, could simply be rewound on take-up reels for coiningelsewhere.

Referring to FIG. 4 two coils of pre-punched nickel silver strip Aprovide springs arranged across the strips with the contact positionsalong one edge. FIG. shows clearly a typical spring configuration havingslots 34 and 35 to engage with feed sprockets B for synchronouslyadvancing the pre-punched strip to the welding and cutting stations.Coils C of precious metal wire (e.g. 0.85 m/m diameter) are mounted onthe billet producing unit, above a wire feeder and turret such as isshown schematically in FIG. 3.

Upon starting the machine the strips feed forward in unison and atconstant speed. At the same time the wires (such as l) are fed and cutto produce billets (see FIG. 3) of a preset length. The wires arecarried round in the turret and during its revolution feed forward inpreparation for the next cut, while the billets are carried in thecarrier plate 24 to meet the spring strip at the welding station D. Theend of each individual contact spring locates in a nest (not shown) onthe billet carrier plate to ensure accurate location of the billet withrespect to the contact springs. When a spring and billet assemblyarrives at the welding station the electrodes grip the assembly andtravel with it during the welding cycle.

The two strips now joined by a billet at each contact position continuethrough the machine to the cutting station E where the two rotary bladescut the billets into half, thus separating the spring strips and leavingchisel-shaped contacts on each strip. The strips are then rewound ontoindividual take-up reels.

The final coining of the contacts can be performed at a later stage,when the strips are cut into individual springs. The welding current canbe monitored as every billet is welded to give an immediate indicationof the condition of the weld and the machine can be arranged toautomatically stop if a fault occurs.

Referring now to FIG. 6 there is shown one embodiment of weldingapparatus which would be situated above the strips of contact springs asthey pass through the welding station. Below the strips would be asimilar piece of welding apparatus working synchronously with the oneshown.

The apparatus comprises an electrode carrier 36 carrying an electrode37. The carrier is mounted on flexures 38 connected to a block 38amounted on a beam 39. The beam 39 is pivotably connected at 40 and 41 torespective depending beams 42 and 43 pivotably connected to a frame (notshown) at 44 and 45. A compression spring arrangement 46 acts between acam 47 and the top of the electrode carrier 36. This cam 47 imparts upand down motion to the electrode while a second cam 48 impartshorizontal motion to the electrode.

In operation the cams co-operate to drive the electrode tip 37 over theclosed loop a, b, c, d indicated by the dotted line in the Figure. At athe electrode tip is positioned just above the tip of a contact springabout to be welded and proceeds down into contact with the strip atposition b, through the combined action of the cams 47 and 48, springarrangement 46 and slight flex ure of the flexures 38. From b to c theelectrode tip is held in contact with the spring contact and weldcurrent is applied to weld the contact to the contact spring. At 0, thecam 47 allows the electrode tip to rise to position d away from thecontact spring and then cam 48 causes the tip to return through the loopback to position a to commence a further weld on a subsequent contactspring.

As stated above a similar apparatus would operate beneath the contactspring in a similar mode.

Referring now to FIG. 7 an alternative apparatus is shown for high speedcontact welding utilizing separate contact springs, i.e. springs whichare not integral with the strip from which they are punched. Referringto the drawing at the left hand end the machine comprises a doublefeeder unit A which feeds two prepunched springs from the springmagazines B to the transfer track C. A transfer mechanism (shown moreclearly in FIG. 8) moves the springs along the track to the operatingstations. The first operating station is the welding heads D' (one aboveand one below) and, to one side of the transfer track there is theprecious metal wire feed unit E from which the individual billets arecut (shown in greater detail in FIGS. 9 and 10). Further along asplitter cut station F separates the two springs which have been weldedtogether via a pair of billets and the spring contacts are coined at thecoining unit G. Finally the individual springs are stacked on stackingstems H.

This machine differs from the one described earlier also in that thewelding head does not move with the contact springs neither does theprecious metal wire feed unit E rotate. This also is fixed and the wholeprocess is a step-by-step process, the operations at the variousstations taking place while the transfer of the springs has temporarilyhalted.

Referring now to FIG. 8 the feed of the individual contact springs isshown on a larger scale and in greater detail, although still somewhatschematically.

In FIG. 8 the initial part of the feeding unit A comprises a rotatingcrank 50 with a connecting rod 51 driving a feeding tongue 52 to and frosinusoidally. A spring magazine 53 (one of the magainzes B in FIG. 7)feeds the springs in front of the tongue 52 which projects them forwardso that the springs such as 54 become engaged by a feeding arm 55 drivenin orbital fashion by a crank 56. The arm 55 has a plurality of teeth 57which drives the springs such as 54 along by their rear edge. In orderto ensure that the spacing and positioning is accurate a guiding arm 58is driven up and down by a connecting rod 59 and a rotating crank 60.This arm 58 has a plurality of teeth 61 having tapered ends such as 62.The synchronization of the movement of the arms 55 and 58 and the tongue52 is indicated on their respective crank positions by the letters a, band c.

Although not shown a second feed of contact springs from the second ofthe magazines B (FIG. 7) is positioned just below those shown in FIG. 8and separated by the track plates. Arms similar to 55 and 58 would bepositioned upside down with reference to FIG. 8 to feed the underlyingrow of springs in synchronism with the first row shown in FIG. 8. Asillustrated in FIG. 7 the feed unit A has two tongues (each similar to52 in FIG. 8) for feeding from the respective magazines.

Referring now to FIG. 9 there is shown perspectively and schematically awire feed unit E and one of the welding heads D. The arrangement issomewhat similar to that shown in FIG. 3 except that only two preciousmetal wires 63 and 64 are fed to provide the billets in pockets such as65 in a billet carrier wheel 66. In the position shown in FIG. 9, aflying cutter arm 67 having two cutting wheels 68 and 69 will rotateanticlockwise about the pivot 70 sufficient to cut the two wires 63 and64 just above the pockets in the wheel 66 in which the wires arepositioned. The arm 67 returns then to its position shown in the Figureand the wheel 66 rotates clockwise about the pivot 70 through one step,i.e. to a position where the next pair of pockets 65 is situated beneaththe wires 63 and 64 to receive the end portions of the wires.

The cut billets are carried around by the wheel 66 to the position ofthe welding head D. As shown contact springs 54 are advanced so that atthe welding position their contact head portions just overlie the wheel66 to receive a pair of billets. As the contact springs are advanced tothe welding position their contact tip portions ride up a ramp so thatat the welding position the contact tip portions rest on the tips of therespective billets. A similar feed of contact springs is also fed justbeneath those shown in FIG. 9 so that their contact tip portions overliethe other side of the wheel 66 in a corresponding position. The weldinghead D' welds the contact spring 54' to a corresponding spring beneathit via the two contact billets and this is shown by the referencenumeral 54".

In FIG. 9A the contact tip portions of the two contact springs 54" heldtogether by their welded contact billets 55 and 56 are shown in greaterdetail (each similar to the contact billet 3 shown in the sequency ofevents in FIGS. lA-lG). A guiding and feeding arrangement (not shown inFIG. 8) would be used to guide the contact wires 63 and 64 accuratelyinto the pockets such as 65 in the wheel 66.

The step-wise movement of the wheel 66, the motion of the cutter 67, thefeed mechanism for feeding the wires 63 and 64 (not shown) and theoperation of the welding heads D would all be synchronized with thestep-wise transfer motion of the contact springs 54. This of courseapplies to the splitter cutters F and the coining unit 0' shown in FIG.7. All such operations are carried out while the springs or contactbillets are stationary and this is one of the main distinguishingfeatures between this arrangement and that described with reference tothe earlier figures.

Referring now to FIG. 10, which is a section in the direction of thearrows on the line X-X shown in FIG. 9, but with the flying cutter arm67 on the point of cutting a billet from the wire 63. It is emphasizedthat once again the drawing is mainly schematic. The cutter wheels 68and 69 are rotated in mutually opposite directions as they approach thewire 63 so that as the wheel peripheries touch the is 63 there is littleor no relative movement between the peripheries of these wheels and thewire 63. This ensures a clean cut of the wire 63 with the cuttingperipheries. A billet 71 (similar to 3, 56 and 55 of the other figures)is thus cut from the wire and is held in position in the pocket 65 ofthe wheel 66 and a guide wall 72 ensures that the billet does not fallout of the pocket during rotation of the wheel 66 to transfer the billetto the welding station D. The FIG. 10, being schematic, does not showassociated driving gearwheels etc, which would be required to drive thecutter wheels 68 and 69 and to rotate the am 67 and also to drive thecarrier wheel 66.

The specifications of the manufacturing process and apparatus of thisinvention which have been described herein, are given by way of exampleonly, and are not meant in any way to limit the scope of this invention.

What is claimed is:

1. A method of manufacturing contact springs comprising the followingsteps:

a. locating a billet of contact material between two springs;

b. supporting the billet and the springs so that the billet contacts thesprings;

c. passing an electric welding current through said contact and springsto weld the billet to both said springs; and

d. forming the billet into two separate portions so that each springcontains a contact made from said billet.

2. The method according to claim 1 wherein said springs are bifurcatedand wherein two said billets are each welded to both said springs, eachsaid billet being subsequently formed into separate portions so thateach said spring contains two contacts made from said two billets, eachsaid one contact on each spring portion formed by the bifurcationthereof.

* l I I! i

1. A method of manufacturing contact springs comprising the followingsteps: a. locating a billet of contact material between two springs; b.supporting the billet and the springs so that the billet contacts thesprings; c. passing an electric welding current through said contact andsprings to weld the billet to both said springs; and d. forming thebillet into two separate portions so that each spring contains a contactmade from said billet.
 2. The method according to claim 1 wherein saidsprings are bifurcated and wherein two said billets are each welded toboth said springs, each said billet being subsequently formed intoseparate portions so that each said spring contains two contacts madefrom said two billets, each said one contact on each spring portionformed by the bifurcation thereof.